Copolymers of ethylene and ethylenically unsaturated monomers, process for their preparation and distillate oil containing said copolymers

Abstract

Polymers of 1,000 to 50,000 and preferably of 1,000 to 2,900 number average molecular weight, comprising 3 to 40 molar proportions of ethylene per molar proportion of an ethylenically unsaturated monomer, are prepared by free radical catalysis in a solvent at temperatures of less than 130 DEG C. in order to minimize ethylene branching, for use as wax crystal modifying agents, e.g. pour depressants and flow improvers for distillate mineral oil, e.g. middle distillate fuel oil.

What is claimed is: 
     
       1. A distillate petroleum fuel oil boiling in the range of 250° F. to 750° F. containing about 0.001 to 2 wt. % of a wax crystal modifier which has a number average molecular weight of about 1,000 to 50,000 and is a copolymer consisting of 3 to 40 molar proportions of ethylene and one molar proportion of ester of the general formula: ##STR2## wherein: (a) R 1  is selected from the group consisting of hydrogen and methyl radicals; (b) R 2  is selected from the group consisting of --OOCR 4  and --COOR 4  groups;   (c) R 3  is hydrogen, and   (d) R 4  is a C 1  to C 4  alkyl group; which copolymer has less than 6 methyl terminating side branches per 100 methylene groups other than methyl groups on said ester, said copolymer being prepared by copolymerizing said monomers in an inert solvent by free radical catalysis at a temperature of about 70° to 130° C. using a catalyst having a half life at 130° C. under 1 hour and under pressure of 500 to 10,000 psi.   
     
     
       2. A distillate oil according to claim 1, wherein said temperature is in the range of 80° to 125° C. and said pressure is about 700 to 3000 psig. 
     
     
       3. A distillate oil according to claim 1, wherein said ester is vinyl acetate. 
     
     
       4. A distillate oil according to claim 3, wherein said molecular weight is about 1,000 to 2,900. 
     
     
       5. A distillate oil according to claim 1 wherein said copolymer is a random copolymer having a number average molecular weight of 1,000 to 2,900 of 3 to 20 molar proportions of ethylene per one molar proportion of vinyl acetate, characterized by about two methyl terminating side branches per 100 methylene groups as measured by nuclear magnetic resonance other than the methyl groups on the vinyl acetate. 
     
     
       6. A distillate oil according to claim 5, wherein said copolymer has been formed by copolymerizing said ethylene and vinyl acetate in solvent at a temperature in the range of about 70° to 130° C. using dilauroyl peroxide catalyst. 
     
     
       7. A distillate petroleum fuel oil boiling in the range of 250° F. to 750° F. containing about 0.001 to 2 wt. % of a wax crystal modifier which has a number average molecular weight of about 1,000 to 50,000 and is a copolymer consisting of 3 to 40 molar proportions of ethylene and one molar proportion of ester of the general formula: ##STR3## wherein: (a) R 1  is selected from the group consisting of hydrogen and methyl radicals; (b) R 2  is selected from the group consisting of --OOCR 4  and --COOR 4  groups;   (c) R 3  is hydrogen, and   (d) R 4  is a C 1  to C 4  alkyl group; which copolymer is characterized by about two methyl terminating side branches per 100 methylene groups other than methyl groups on said ester.     
     
     
       8. A distillate petroleum fuel oil according to claim 7, wherein said molecular weight is about 1,000 to 2,900.